Fluorescein has a pKa value of 6.4, and excitation / emission maxima at 492
/ 516 nm respectively. At pH 6.2 its fluorescence will not be dramatically
reduced vs. fluorescence at pH 7.4.
Molecular Probes, Inc. recently developed a series of fluorescein analogs
with lower pKa values and increased photostability.
These will become commercially available in the fall of this year.
Please inquire at :
Molecular Probes, Inc.
P.O. Box 22010
Eugene OR 97402
Tel : +1 - 503 - 465 - 8300 (request Technical Assistance Department)
In Europe, Tel : +31 - 71 - 233 431
Martin Poot
martin@probes.mhs.compuserve.com